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Description of Business - Additional Information (Detail) songwriter in Thousands, musical_composition in Millions |  |  | 3 Months Ended |
--- | --- | --- | --- | ---
Jul. 07, 2020 shares | Jun. 05, 2020 $ / shares shares | Dec. 31, 2020 country musical_composition $ / shares songwriter shares | Sep. 30, 2020 $ / shares
Subsidiary, Sale of Stock [Line Items] |  |  |  |
Number of countries in which Recorded Music activity conducted (more than) | country |  |  | 70 |
Minimum number of musical compositions on which Company owns or controls rights (more than) | musical_composition |  |  | 1,000,000 |
Number of songwriters and composers (over) | songwriter |  |  | 80 |
Access Industries |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |
Percentage of voting power |  | 99.00% |  |
Percentage of economic interest |  | 83.00% |  |
Class A Common Stock |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |
Par value (in dollars per share) |  |  | $ 0.001 | $ 0.001
Class B Common Stock |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |
Par value (in dollars per share) |  |  | 0.001 | $ 0.001
Class B Common Stock | Access Industries |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |
Par value (in dollars per share) |  |  | $ 0.001 |
Investment owned (in shares) | shares |  |  | 421,450,000 |
IPO | Class A Common Stock |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |
Number of shares issued in transaction (in shares) | shares |  | 77,000,000 |  |
Par value (in dollars per share) |  | $ 0.001 |  |
Price per share (in dollars per share) |  | $ 25 |  |
Over-Allotment Option | Class A Common Stock |  |  |  |
Subsidiary, Sale of Stock [Line Items] |  |  |  |
Number of shares issued in transaction (in shares) | shares | 11,550,000 |  |  |

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